The present invention relates generally to instruments for determining penetration rates through a membrane, and more specifically to an instrument for determining the penetration rate of chemicals through biological membranes in vitro.
The rate of penetration of chemicals through biological membranes is an important factor in studying the possible harmful effects of various chemicals that come into contact with the skin. The determination of penetration rates is particularly important in determining exposure limits for workers in the pharmaceutical, pesticide and other chemical industries.
Penetration rates are generally determined with an instrument that places a selected membrane between a receptor solution and a selected test chemical. After a period of time, the receptor solution is analyzed for the presence of any test chemical that has penetrated the membrane. Present instruments for determining penetration rates are generally made of glass and are fragile, difficult to use, and unreliable. A particular problem with present instruments is that chambers for flowing receptor solution past the membrane allow bubbles to become stalled or trapped inside the chambers, thus interfering with the reliability and reproducibility of the results. This is particularly demonstrated in that present instruments show markedly different test results when tapped or shaken to free trapped bubbles.
Another problem with present instruments is membrane viability. Many present instruments do not provide for the delivery of glucose or other nutrients to maintain the viability of the biological membrane under test to ensure test results more closely related to that of living tissue.
It is seen, therefore, that there is a need for an improved test instrument for determining in vitro the penetration rate of chemicals across biological membranes without the problems of prior art instruments.
It is, therefore, a principal object of the present invention to provide a test instrument for determinig in vitro the penetration rate of chemicals across biological membranes that prevents the trapping or stalling of bubbles in the receptor solution and that provides consistent reproducible test results.
It is another object of the present invention to provide a test instrument for determining in vitro the penetration rate of chemicals across biological membranes that maintains the viability of the tested membrane.
It is a feature of the present invention that it provides for automatically stretching the biological membrane taut over the opening to the reservoir solution chamber.
It is another feature of the present invention that the temperature under which penetration tests are conducted may be conveniently controlled by simple placement of the entire apparatus into a standard, commercially available, dry temperature bath.